The invention relates to a ringlift crane.
A ringlift crane of the generic design is known from the Mannesmann Demag Baumaschinen company brochure entitled xe2x80x9cRinglift Cranesxe2x80x9d CC 2000 RL; CC 4000 RL, issue 11/82. This known ringlift crane has a ring which can be elevated, forms an annular track and comprises a plurality of segments which can be connected to one another. Arranged within the ring is an undercarriage and an upper carriage, which is connected for slewing action to the undercarriage and has a plurality of hoisting winches. In the two end regions, the upper carriage is connected to in each case one adapter, and these adapters are supported with rolling action on the annular track of the ring by means of sets of rollers which are arranged on the adapters and are connected to one another via links. In this case, the center point of the ring and/or of the undercarriage forms the slewing axis. One adapter is designed for accommodating a counterweight and the other adapter is designed as a load-bearing element for a boom (main boom+mast) which can be articulated at the free end of the adapter. The slewing movement of the ringlift crane is produced by means of a toothed rim, which is arranged on the inside of the ring, and pinions which engage in said rim and are mounted via links. For the purpose of stabilizing the overall structure, the undercarriage is connected to different sections of the ring via reinforcing struts. The tip of the mast is connected, on the one hand, to the counterweight via a stay cable and, on the other hand, to the head of the main boom via a changeable-length cable stay.
A comparable design is known from U.S. Pat. No. 4,103,783. This ringlift crane comprises a ring, which can be elevated and forms an annular track, and a structure within the ring with a kingpin and a platform which is provided with a sleeve for accommodating the kingpin. In the two end regions, the platform is connected to in each case one adapter, these adapters being supported with rolling action on the ring by means of sets of rollers arranged on the adapters, the center point of the ring forming the slewing axis for the platform. A plurality of hoisting winches are arranged on the platform and a counterweight is arranged on the rear adapter. A main boom and a mast (counter-boom) are articulated on the front adapter. The single-part ring is stiffened by struts which run within the ring in secant form.
According to the prior art, ringlift cranes of the type explained above acquire a high-outlay assembly and dismantling procedure in order to be erected or laid down, respectively.
The object of the invention is to provide a ringlift crane which can easily be erected and laid down.
According to the invention, a stay support is arranged on that side of the mast which is directed toward the counterweight. The free end of the stay support is connected to the free end of the load-bearing bars of the counterweight via a changeable-length cable stay. The free end of the cable stay is connected, in turn, to an auxiliary hoisting winch arranged on the load-bearing element. This arrangement makes it possible for the mast and the main boom to be erected and laid down easily. In order that there is no adverse effect to the normal hoisting-winch operation, in particular for the hoist cable, it is preferable for both the stay support and the auxiliary hoisting winch to be arranged on one side, outside the operating region of the main hoisting winches.
The stay support and auxiliary hoisting winch are connected via a cable drive with sets of rollers arranged correspondingly at the free end of the stay support and on the load-bearing bars. The length and the point of articulation on the mast of the stay support is selected such that, once the mast has been erected, the head region of the stay support can be laid down on the counterweight. This has the advantage that the hoisting-winch operation also remains freely accessible from the side of the stay support.